"Fairly Simple" depends on your perspective. I have been skating for four and a half years and I consider 360 flips a pretty simple trick for me, but I remember the days of practice it took to learn this one. Now that I look back on it, 360 flips did in fact, take me almost a year to learn and two years to really master. All the hard work paid off because I can do them virtually every try now, and I can do them switch too. Switch means doing a trick using your unnatural stance. The way M-I-K-E describes how to do the trick is correct but putting the tip of your foot at the edge of your board is not advised. I learned this trick that way, but I eventually had to relearn 360 flips with the tip of my foot more in the center of the board, which makes it easier to balance, and gives you a better looking 360 flip that goes higher off the ground. It is easier to learn it with the tip of your foot at the side but eventually you want to learn it the way I described so you can have a more developed and functional trick. When you try to do the trick with your toes near the edge you often fall over because you are so far back and to the side of your board. You know you have fully mastered this trick when you can do it with your front-foot right below the front truck bolts.
Rodney Mullen invented this trick sometime during the 80's. Skaters who are known for having very nice 360 flips are Jason Lee, Pat Chinita and Josh Kalis among many others. Arto Saari has a very distinguished switch 360 flip along with Brian Wenning as well. Overall 360 flips are a very stylish trick which take a lot of practice to learn, but one you learn them they are not that hard. Switch 360 flips are insanely hard and are very respected.